At least partially implantable hearing system

ABSTRACT

An at least partially implantable hearing system comprising at least one electromechanical output transducer; a micromanipulator for positioning the transducer and for fixing the transducer in a position set by the micromanipulator, the micromanipulator being adapted to be fixedly attached by fixing means to a skull cap; and a releasable coupling unit disposed between the transducer and the micromanipulator, said coupling unit, in an assembled state, fixing the transducer with respect to the micromanipulator, and, in a released state, permitting removal of the transducer from the micromanipulator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an at least partially implantable hearingsystem comprising at least one electromechanical output transducer and amicromanipulator for positioning the transducer and for fixing thetransducer in a position set by the micromanipulator, themicromanipulator being adapted to be fixedly attached by fixing means toa cranial vault.

2. Description of Related Art

The expression “at least partially implantable hearing system” isdefined here as a system in which a sound signal is picked up by atleast one sensor which transduces a sound signal into an electricalsignal (microphone function), in which this electrical signal iselectronically further processed and amplified, and in which an outputsignal of the system causes an electromechanical stimulation of thedamaged hearing, wherein at least one component of the system,particularly the electromechanical output transducer, is designed forbeing implanted.

The expression “hearing dsefder disorder” is defined here as includingany type of inner ear and middle ear damage, any combined inner ear andmiddle ear damage, and a temporary or permanent noise impression(tinnitus).

Hearing systems of the presently considered type usually comprise atleast one acoustic sensor (microphone) for picking up acoustic signalsand converting them into electrical audio sensor signals, an electronicsignal processing unit for audio signal processing and amplification, anelectrical power supply unit which supplies individual components of thesystem with energy, and an electromechanically actoric outputarrangement including at least one electromechanical transducer forstimulation of the middle and/or inner ear. This transducer is connectedto a mechanical positioning and fixing system which here is termed“micromanipulator” and which is fixedly and permanently attached to thecranial vault. In the case of a fully implantable hearing system inwhich the implant is provided with a secondary storage element forelectrical energy, the system further comprises a wirelesstranscutaneoiis charging device.

Electronic measures for rehabilitation of inner ear damage which cannotbe cured by surgery have currently achieved great importance. With totalfailure of the inner ear, cochlear implants with direct electricalstimulation of the remaining auditory nerves are in routine clinicaluse. For medium to severe inner ear damage, for the first time, fullydigital hearing devices are presently being used which open up a newworld of electronic audio signal processing and offer expandedpossibilities of controlled audiological fine tuning of the hearingdevices to the individual inner ear damage. In spite of majorimprovements of hearing aid hardware achieved in recent years, inconventional hearing aids, there remain basic defects which are causedby the principle of acoustic amplification, i.e. especially by thereconversion of the electronically amplified signals into airbornesound. These defects include aspects such as the visibility of thehearing aids, poor sound quality as a result of electromagnetictransducers (speakers), closed external auditory canal as well asfeedback effects at high acoustic gain.

As a result of these fundamental defects, there has long been the desireto move away from conventional hearing aids with acoustic stimulation ofthe damaged inner ear and to replace them by partially or fullyimplantable hearing systems with direct mechanical stimulation.Implantable hearing systems differ from conventional hearing aids: theacoustic signal is converted with a proper microphone into an electricalsignal and amplified in an electronic signal processing stage; thisamplified electrical signal, however, is not sent to anelectroacoustical transducer (speaker), but rather to an implantedelectromechanical transducer providing for output-side mechanicalvibrations which are sent directly, and therefore with direct mechanicalcontact, to the middle ear or inner ear, or indirectly via an air gapin, for example, electromagnetic converter systems. This principleapplies regardless of whether implantation of all necessary systemelements is partial or complete and also regardless of whether anindividual with pure inner ear impairment with a completely intactmiddle ear or an individual with combined hearing impairment, in whichthe middle and inner ear is damaged, is to be rehabilitated. Thereforeimplantable electromechanical transducers and methods for coupling themechanical transducer vibrations to the functioning middle ear ordirectly to the inner ear for rehabilitation of a pure inner earimpairment, or to a remaining ossicle of the middle ear in the case ofan artificially or pathologically altered middle ear for taking care ofa hearing disorder caused by a disturbance of sound conduction, or forcombinations of such disorders, have been described in the recentscientific literature and in many patents.

Useful electromechanical transducer processes include basically allphysical transducer principles, such as electromagnetic, electrodynamic,magnetostrictive, dielectric and piezoelectric. Various research groups,in recent years, have focused essentially on two of these processes,namely electromagnetic and piezoelectric processes. A survey can befound in H. P. ZENNER and H. LEYSIEFFER (HNO 10/1997, vol. 45, pp.749–774).

In the piezoelectric process, direct mechanical coupling of theoutput-side transducer vibrations to the middle ear ossicle or to theoval window is essential. In the electromagnetic principle, forcecoupling between the transducer and ossicle, on the one hand, can takeplace “without contact”, i.e. via an air gap; in this case, only thepermanent magnet is caused to vibrate by the transducer being in directmechanical contact with the middle ear ossicle by permanent fixation. Onthe other hand, it is possible to implement the transducer entirely in ahousing (in this case the coil and the magnet preferably being coupledwith the smallest possible air gap) and to transmit the output-sidevibrations via a mechanically stiff coupling element with direct contactto the middle ear ossicle (see FREDRICKSON et al.: Ongoinginvestigations into an implantable electromagnetic hearing aid formoderate to severe sensorineural hearing loss; Otolaryngologic Clinicsof North America, Vol. 28/1 (1995), pp. 107–121; and H. Leysieffer etal., HNO 10/97, vol. 45, pp. 792–800).

The patent literature contains some of the aforementioned versions ofboth electromagnetic and also piezoelectric hearing aid transducers:U.S. Pat. No. 3,712,962, EPLEY; U.S. Pat. No. 3,870,832, FREDRICKSON;U.S. Pat. No. 3,882,285, NUNLEY et al.; U.S. Pat. No. 4,850,962,SCHAEFER; U.S. Pat. No. 5,015,224, MANIGLIA; U.S. Pat. No. 5,277,694,LEYSIEFFER et al.; U.S. Pat. No. 5,554,096, BALL; U.S. Pat. No.5,707,338, ADAMS et al.; U.S. Pat. No. 6,123,660, LEYSIEFFER; U.S. Pat.No. 6,162,169, LEYSIEFFER; International Patent Application PublicationsWO-A 98/06235, ADAMS et al.; WO-A 98/06238, ADAMS et al.; WO-A 98/06236,KROLL et al.; WO-A 98/06237, BUSHEK et al.

The partially implantable piezoelectric hearing system of the Japanesegroup of Suzuki and Yanigahara presupposes, for implantation of thetransducer, the absence of the middle ear ossicles and a free tympaniccavity to be able to couple the piezo element to the stapes (Yanigaharaet al.: Efficacy of the partially implantable middle ear implant inmiddle and inner ear disorders: Adv. Audiol., Vol. 4, Karger Basel(1988), pp. 149–159; Suzuki et al.: Implantation of partiallyimplantable middle ear implant and the indication. Adv. Audiol., Vol. 4,Karger Basel (1988), pp. 160–166). Likewise, in the method of implantinga hearing system for inner ear hearing-impaired according to SCHAEFER(U.S. Pat. No. 4,850,962) basically the incus is removed in order to beable to couple a piezoelectric transducer element to the stapes. Thisalso applies to further developments which are based on the SCHAEFERtechnology and which are described in the above mentioned patents (U.S.Pat. No. 5,707,338, ADAMS et al.; International Patent ApplicationPublications WO-A 98/06235, ADAMS et al.; WO-A 98/06238, ADAMS et al.;WO-A 98/06236, KROLL et al.; WO-A 98/06237, BUSHEK et al.).

The BALL electromagnetic transducer (“Floating Mass Transducer FMT” ofU.S. Pat. No. 5,554,096, BALL; U.S. Pat. No. 5,624,376, BALL et al.) is,on the other hand, directly fixed to the long process of the incus whenthe middle ear is intact. The electromagnetic transducer of thepartially implantable system of FREDRICKSON (Fredrickson et al.: Ongoinginvestigations into an implantable electromagnetic hearing aid formoderate to severe sensorineural hearing loss, Otolaryngologic Clinicsof North America, Vol. 28/1 (1995), pp. 107–121) is directlymechanically coupled to the body of the body of the incus when theossicular chain of the middle ear is likewise intact. The same appliesto the piezoelectric transducers of LEYSIEFFER (LEYSIEFFER et al.: Animplantable piezoelectric hearing aid converter for the inner earhearing-impaired. HNO 1997/45, pp. 792–800; U.S. Pat. No. 5,277,694,LEYSIEFFER et al.; U.S. Pat. No. 6,123,660, LEYSIEFFER; U.S. Pat. No.6,162,169, LEYSIEFFER). Also in the electromagnetic transducer system ofMANIGLIA (MANIGLIA et al.: Contactless semi-implantable electromagneticmiddle ear device for the treatment of sensorineural hearing loss,Otolaryngologic Clinics of North America, Vol. 28/1 (1995), pp. 121–141)with the ossicular chain intact a permanent magnet is permanentlymechanically fixed to the ossicular chain, but is mechanically drivenvia an air gap coupling by a coil.

In the described transducer and coupling versions, basically, twoimplantation principles can be distinguished:

-   a) In the case of the one principle the electromechanical transducer    with its active transducer element is located itself in the middle    ear region in the tympanic cavity and the transducer is directly    connected there to an ossicle or to the inner ear (U.S. Pat. Nos.    4,850,962, 5,015,225, 5,707,338, 5,624,376, 5,554,096, and    International Patent Application publication Nos. WO 98/06235, WO    98/06238, WO 98/06236, and WO 98/06237).-   b) In the other principle the electromagnetic transducer with its    active transducer element is located outside of the middle ear    region in an artificially formed mastoid cavity; the output-side    mechanical vibrations are then transmitted to the middle or inner    ear by means of mechanically passive coupling elements via suitable    surgical accesses (the natural aditus ad antrum (U.S. Pat. No.    6,077,215), opening of the chorda-facialis angle or via an    artificial hole from the mastoid (Fredrickson et al.: Ongoing    investigations into an implantable electromagnetic hearing aid for    moderate to severe sensorineural hearing loss. Otolaryngologic    Clinics of North America, Vol. 28/1 (1995), pp. 107–121; U.S. Pat.    No. 5,277,694; U.S. Pat. No. 6,123,660; U.S. Pat. No. 6,162,169).    This type of access requires an implantable positioning and fixing    system (micromanipulator) for “suspending” the electromagnetic    transducer, wherein the positioning and fixing system is to be    fixedly and durably attached to the skull (U.S. Pat. No. 5,788,711    and commonly owned U.S. patent application Ser. No. 09/468,853).

An advantage of the a) type versions is, that the transducer can be madeas a so-called “floating mass” transducer, i.e., the transducer elementdoes not require any “reaction” via secure screwing to the skull bone,but it vibrates based on the laws of mass inertia with its transducerhousing and transmits these vibrations directly to a middle ear ossicle(U.S. Pat. Nos. 5,624,376, 5,554,096, and 5,707,338, and InternationalPatent Application publication no. WO 98/06236). On the one hand, thismeans that an implantable fixation system on the cranial vault can beadvantageously omitted; on the other hand, this versiondisadvantageously means that bulky artificial elements must be placed inthe tympanic cavity, and their long-term stability and biostability arecurrently not known or guaranteed, especially in the case of temporarypathological changes of the middle ear (for example, otitis media).Another major disadvantage is that the transducer together with itselectrical supply line has to be transferred from the mastoid into themiddle ear and must be fixed there using suitable surgical tools; thisrequires an expanded access through the chorda facialis angle, and thus,entails a latent hazard to the facial nerve which is located in theimmediate vicinity. Furthermore, such “floating mass” transducers can beused merely in a very limited manner or not at all, when the inner earis to be directly stimulated for example via the oval window, or when,due to pathological changes, for example the incus is substantiallydamaged or is no longer present, so that such a transducer no longer canbe mechanically connected to an ossicle that is able to vibrate and isin connection with the inner ear.

A certain disadvantage of the transducer versions as per b) is that thetransducer housing is to be attached to the cranial vault with the aidof implantable positioning and fixation systems (micromanipulators)(advantageous embodiment U.S. Pat. No. 5,788,711). A furtherdisadvantage of the transducer versions as per b) is that a recess is tobe made, preferably by an appropriate laser, in the respective ossiclein order to allow the application of the coupling element. This, on theone hand, is technically complicated and expensive and, on the otherhand, involves risks for the patient. Both in the partially implantablesystem of FREDRICKSON ( “Ongoing investigations into an implantableelectromagnetic hearing aid for moderate to severe sensorineural hearingloss”, Otolaryngologic Clinics of North America, Vol. 28/1 (1995), pp.107–121) as well as in the fully implantable hearing system ofLEYSIEFFER and ZENNER (HNO 1998, vol. 46, 853–863 and 844–852), when thevibrating transducer part is coupled to the body of the incus, it isassumed that for permanent and mechanically secure vibrationtransmission the tip of the coupling rod which is placed in thelaser-induced depression of the middle ear ossicle undergoesosseointegration over the long term, i.e., the coupling rod coalescessolidly with the ossicle and thus ensures reliable transmission ofdynamic compressive and tensile forces. However, this long-term effectis currently not yet scientifically proven or certain. Furthermore, inthis type of coupling, in case of a technical transducer defect, thereis the disadvantage that decoupling from the ossicle to remove thetransducer can only be done with mechanically based surgical methods;this can mean considerable hazard to the middle ear and especially theinner ear. Therefore further coupling elements, partly involving novelsurgical access paths, were developed which minimize or no longer havethe above mentioned disadvantages (U.S. Pat. No. 5,941,814, LEHNER etal., commonly owned U.S. patent applications Ser. Nos. 09/576,009;09/613,560; 09/626,745; 09/680,489).

The major advantages of these converter embodiments as per b), however,are that the middle ear remains largely free, and that access to themiddle and inner ear can take place in a manner which permits, whenusing a properly designed micromanipulator, reaching of basically anypoint of the middle ear or of the inner ear, respectively, asstimulation site. One preferable surgical process for this purpose isdescribed in U.S. Pat. No. 6,077,215, LEYSIEFFER. This results in thefurther advantage that basically all combinations of middle and innerear damages can be attended, and that a pure inner ear stimulationlikewise is possible via a direct access, for example an artificialwindow, and by using proper coupling elements. In this connection adetachable interconnection between transducer and coupling element hasbeen disclosed in commonly owned U.S. patent application Ser. No.09/680,489.

In a hearing system known from International Patent ApplicationPublication WO 00/48426 a unit consisting of an actoricelectromechanical transducer and of a positioning and fixation system(here called “micromanipulator”) is detachably connected to mountingmeans fixedly attached to the skull, so that in case of need themicromanipulator together with the transducer may be exchanged withoutdisassembly of the mounting means being required. In fact, the removalof the mounting means may require a relatively invasive interventionbecause the operative access to the fixing screws of themicromanipulator must be exposed. Furthermore it my happen that therespective screw holes in the cranial vault can not be reused becausethe screws normally are self-cutting and the respective holes in thebone are widened during unscrewing and no longer can provide for anabsolutely secure seat of new screws. It may also happen that the “old”access path to the point of aim of the transducer coupling element canbe used no longer or only in a very restricted manner. However, theprior solution still leaves much to be desired. Thus, after an exchangeof the micromanipulator/transducer unit this unit must be newly adjustedin a troublesome manner in order to exactly align the transducer withthe aimed site of stimulation. Thereby the reversion operation becomesdistinctly more risky and prolonged, particularly when the transducerpostoperatively became defect and therefore an exchange of thetransducer is required. In addition it may happen that the intervention,which otherwise possibly could take place under local anesthesia, mustbe carried out under total anesthesia because the depth and duration ofthe operation make this necessary. The fixed interconnection betweentransducer and micromanipulator furthermore involves the technicaldrawback that it becomes extremely difficult to find a design for bothcomponents which avoids left-hand/right-hand differences of the system.This leads to the economical disadvantage that for each new implantationtwo complete transducer-micromanipulator systems must be deliveredbecause it may be that only shortly before the operation the decision ismade together with the patient which side will be operated. Anothereconomical disadvantage is that a reversion operation because of adefect of the transducer requires explantation and throwing away of afully functioning micromanipulator because the existing laws prohibit areuse thereof. An other important drawback is that, with the furtherdevelopments of the electromechanical transducers to be expected, suchimproved products again can be offered to a patient already wearing animplant merely in the form of a complete exchange of a system involvingboth the transducer and the micromanipulator.

SUMMARY OF THE INVENTION

A primary object of the present invention is to devise an at leastpartially implantable hearing system which simplifies the measures whichbecome required in case of a defect of the electromechanical outputtransducer, and which system, if desired, also may be retrofitted withan improved transducer in a relatively simple manner.

This object is achieved by an at least partially implantable hearingsystem comprising at least one electromechanical output transducer; amicromanipulator for positioning the transducer and for fixing thetransducer in a position set by the micromanipulator, themicromanipulator being adapted to be fixedly attached by fixing means tothe cranial vault; and a releasable coupling unit disposed between thetransducer and the micromanipulator, said coupling unit, in an assembledstate, fixing the transducer with respect to the micromanipulator, and,in a released state, permitting removal of the transducer from themicromanipulator.

On occurrence of a postoperative transducer defect the releasablecoupling unit provided for in conformity with the invention permits anexchange of the transducer alone, that is without exchanging themicromanipulator, too. The same is true when an exchange of thetransducer becomes desirable for other reasons, for example whenimproved transducers become available due to further developments of thetransducer technology. The transducer position adjusted by themicromanipulator is preserved even in case of an exchange of thetransducer, so that a new adjustment of the micromanipulator does notbecome necessary. In view of the fact that the transducer alone may beexchanged, the above discussed problems with respect toleft-hand/right-hand differences also do not occur.

Furthermore, in conformity with the invention, the releasable couplingpreferably comprises a transducer-side coupling element and amicromanipulator-side coupling element, which coupling elements areadapted to be selectively mechanically engaged with each other anddisengaged from each other, respectively, wherein the transducer-sidecoupling element may be designed for being fixedly connected, forexample adhesively connected, to the transducer already duringproduction of the transducer, or for being fixedly connected to thetransducer, for example by a permanent snap-in connection, in the courseof the implantation of the transducer.

The micromanipulator-side coupling element may define means forreceiving the transducer-side coupling element.

Within the scope of the invention at least one of the coupling elementsmay be at least partially made of elastic material, particularly of asoft polymer, preferably silicone, polytetrafluoroethylene orpolyurethane. Thereby a feedback of body sound from the transducer tothe skull can be prevented or at least reduced. However, dependent onthe design of the coupling, also both coupling elements may be made of ahard polymer, such as a hard polymeric material, a biocompatible metalor a ceramic material.

The releasable coupling unit may be designed as a snap-in coupling,wherein, for example, the micromanipulator-side coupling element is arigid annular receiver member, whilst the transducer-side couplingelement is at least partially elastic and is adapted to snap into therigid annular receiver member in a substantially axial direction. Inconformity with a modified embodiment of a snap-in coupling themicromanipulator-side coupling element comprises an expandable fork, andthe transducer-side coupling element is adapted to be snapped into thisfork in a substantially radial direction.

Furthermore, the micromanipulator-side coupling element may comprise anexpandable receiver member, whilst the transducer-side coupling elementis adapted to be inserted into this receiver member in a substantiallyaxial direction and is adapted to be locked in a position in which thetransducer-side coupling element is detained.

In conformity with a further embodiment of the invention, themicromanipulator-side coupling element may comprise a pair of expandabletongs, and the transducer-side coupling element may be adapted to beintroduced between the tongs in a substantially axial direction, whereinpreferably locking means, for example a sleeve which is mounted forsliding movement along a portion of the tongs, are provided for lockingthe expandable tongs in a closed position in which the transducer-sidecoupling element is detained.

According to a further embodiment of the invention the releasablecoupling unit may comprises a plug-type coupling including a pair ofcoupling elements one of which is adapted to be inserted into the otherone, wherein these coupling elements, in the assembled state of thecoupling, are held engaged with each other by an interference fit. Inthis embodiment one coupling element may include a dovetailed portion,and the other coupling element may include a complementary receivinggroove adapted to receive the dovetailed portion.

Preferably, the micromanipulator, the transducer and the couplingelements are designed in a manner avoiding any left-hand/right-handdifferences, i.e. such that the same combination of micromanipulator andtransducer may be used for the right-hand ear as well as for theleft-hand ear. For this purpose at least one of the two couplingelements may be rotationally symmetrical and/or themicromanipulator-side coupling element may be axially symmetrical withrespect to an axis of the transducer.

Any desired transducer principle may be used within the scope of theinvention. Particularly, the electromechanical output transducer may beselected from the group consisting of electromagnetic, electrodynamic,magnetostrictive, dielectric and piezoelectric transducers and ofcombinations of such transducers.

The described system can be designed to be monaural or binaural, and thecoupling may be designed for being selectively engaged and disengagedmanually or with the aid of a suitable tool

These and further objects, features and advantages of the presentinvention will become apparent from the following description when takenin connection with the accompanying drawings which, for purposes ofillustration only, shows several embodiments in accordance with thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic sectional view of a human petrous bone with atransducer being disposed in a mastoid cavity.

FIG. 2 shows an embodiment of an implantable micromanipulator and of anassociated transducer.

FIG. 3 shows the arrangement of the micromanipulator together with thetransducer within the mastoid cavity.

FIG. 4 a and 4 b show an embodiment of a releasable snap-in coup lingbetween micromanipulator and transducer.

FIGS. 5 a and 5 b show a further embodiment of a releasable snap-incoupling between micromanipulator and transducer.

FIGS. 6 a and 6 b show an embodiment of a releasable plug-type couplingbetween micromanipulator and transducer.

FIGS. 7 a and 7 b show a further embodiment of a releasable plug-typecoupling between micromanipulator and transducer.

FIGS. 8 a and 8 b show an embodiment of a releasable coupling betweenmicromanipulator and transducer comprising a micromanipulator-sidecoupling element which defines an expandable receiver member.

FIGS. 9 a and 9 b show an embodiment of a releasable coupling betweenmicromanipulator and transducer comprising a micromanipulator-sidecoupling element in form of expandable tongs which are adapted for beinglocked in a closed position.

FIG. 10 shows an embodiment of a fully implantable hearing system.

FIG. 11 shows an embodiment of a partially implantable hearing system.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic sectional view of a human petrous boneincluding the external auditory canal 10, the middle ear 11 comprisingthe auditory ossicles malleus, incus and stapes (with the inner ear notbeing illustrated), and an electromechanical transducer 12 which isdisposed in an artificial mastoid cavity 13. The transducer 12, in amanner known per se, is induced to mechanical vibrations, and in thisembodiment the transducer 12 transmits such vibrations to the incus viaa coupling rod 14 which extends through the natural access aditus adantrum. The implantable positioning and fixing system (micromanipulator)is not illustrated in FIG. 1.

FIG. 2 shows an embodiment of an implantable micromanipulator 18 of thetype described in detail in commonly owned U.S. patent application Ser.No. 09/468,853 which is hereby incorporated by reference. Themicromanipulator 18 comprises an osteosynthesis plate 19 which isadapted to be fixed by screws to the cranial vault. Micromanipulator 18further includes a transducer carriage 20 which is provided with amicromanipulator-side coupling element 21. The coupling element 21defines a receiver 23 for the transducer 12. In this embodiment,receiver 23 is in the form of a closed ring. A transducer-side couplingelement 22 is connected to the transducer 12 and, together with themicromanipulator-side coupling element 21 defines a releasable coupling.Transducer 12 connected to coupling element 22 is adapted to be insertedand releasably fixed in the receiver 23.

FIG. 3 shows details of the micromanipulator 18 and of the arrangementthereof, together with the electromechanical transducer 12 releasablyattached thereto, in the implanted state within the mastoid cavity 13.The osteosynthesis plate 19 is securely screwed onto the cranial vault25 by means of bone screws 24. The osteosynthesis plate 19 is rotatably(arrow 29) and pivotally connected to a straight guide rail 28 via aball-and-socket joint 27 having a ball 26. The ball-and-socket joint 27is adapted to be locked by tightening a clamping screw 30 (FIG. 2). Uponloosening of the clamping screw 30, ball 26 can be freely swivelledwithin its socket by a tool 31 in all three rotational degrees offreedom indicated by arrows 29, 32 and 33. A threaded spindle 34 ismounted on the member consisting of ball 26 and guide rail 28 so that itcan be freely rotated, but is prevented from movement in axialdirection. An external thread of threaded spindle 34 is in threadedengagement with an internal thread of a spindle nut which is part of thetransducer carriage 20. The carriage 20, together with transducer 12disposed in receiver 23, can be moved axially along the guide rail 28 byrotating the threaded spindle 34 by means of a tool (not shown). In theillustrated embodiment the longitudinal axis of transducer 12 andcoupling rod 14 extends at least approximately parallel to thelongitudinal axes of threaded spindle 34 and of guide rail 28, but islaterally offset with respect to the longitudinal axis of threadedspindle 34.

FIGS. 4 a and 4 b show an embodiment of a releasable snap-in-lockingtype coupling between micromanipulator 18 and transducer 12. Thetransducer-side coupling element 22 of this coupling is defined by anelastic snout and includes a truncated head 36 having a base 37, acircular cylindrical neck 38 and a collar 39, which follow each other inaxial direction. The base 37 of head 36 has a diameter which is slightlylarger than the diameter of neck 38. Collar 39 radially projects fromneck 38 at the side of neck 38 remote from head 36. The receiver 23defined by the micromanipulator-side coupling element 21 is circularcylindrical and has an inner diameter which is about the same as theouter diameter of neck 38 but is smaller than the diameters of base 37and of collar 39. The axial dimension of neck 38 of the transducer-sidecoupling element 22 is at least approximately equal to the axialdimension of the transducer receiver 23 of micromanipulator 18.

The elastic transducer-side coupling element 22 is adapted to be axiallypushed into the receiver 23 of the micromanipulator-side couplingelement 21, wherein head 36 is slightly deformed. As soon as thetruncated head base 37 of coupling element head 36 again exits thereceiver 23 (in FIGS. 4 a and 4 b in upward direction), the couplingelement 22 snaps into the receiver 23 and is securely mechanicallylocked therein, with the receiver 23 enclosing the neck 38 and themutually facing sides of head 36 and collar 39 abutting the sides 41 and42, respectively, of carriage 20 in the region of receiver 23 (FIG. 4b). When the transducer 12 is to be detached from the micromanipulator18, the head 36 of coupling element 22 may be slightly compressed byhand or with the aid of a proper tool, and the coupling element 22 maybe extracted from the carriage 20 as indicated in FIG. 4 a by arrow 43.

Further embodiments are illustrated in FIGS. 5 to 9, wherein again thereleased state is shown in section a and the assembled state is shown insection b.

FIG. 5 shows a further embodiment of a releasable snap-in-locking typecoupling between micromanipulator 18 and transducer 12 of FIG. 1. Inthis case the carriage 20 comprises a micromanipulator-side couplingelement 45 which is fork-shaped and which defines a receiver 44 for thecoupling element 22 connected to transducer 12. The receiver 44 isradially open at one side thereof The free ends of fork arms 46, 47having essentially the same length delimit a fork opening 48 the widthof which is smaller by a predetermined amount than the outer diameter ofneck 38 of the transducer-side coupling element 22. The fork arms 46, 47may be rigid, if the coupling element 22 is elastic at least within theneck region thereof However, the coupling element 22 also may be rigid,if the coupling element 45 is somewhat elastic. Furthermore both thefork 45 and the transducer-side coupling element 22 may be elasticallyresilient. In any case, the coupling element 22, which in a manner notshown in more detail is connected to transducer 12, may be snapped intothe receiver 44 and locked therein by being moved in a direction whichis radial to the axis of the coupling element. A movement of thecoupling element 22 in the opposite direction (arrow 49) permitsdetaching the coupling element 22 from the receiver 44.

FIG. 6 shows an embodiment of a releasable plug-type coupling betweenthe micromanipulator 18 and the transducer 12 of FIG. 1. In this casethe carriage 20, different from the illustration in FIGS. 2 and 3,comprises a micromanipulator-side coupling element 50 which is widenedin a dovetailed manner at its free end 51 and which is adapted to beslid (arrow 55) into a complementary receiving groove 52 of a couplingelement 54 connected to the transducer 12 (not shown in FIG. 6).Receiving groove 52 is open at one end thereof (the upper end in FIG.6). An end wall 56 of receiving groove 52, which is opposite to the openend of the groove, defines a stop for the coupling element 50. In thisembodiment both the transducer-side coupling element 54 and themicromanipulator-side coupling element 50 may be mechanically rigid. Inthis case the interconnection between transducer and micromanipulator iseffected by a combined form-locking and frictional locking engagement.However, it is also possible that at least one of the elements 50, 54 iselastic at least within the respective coupling region.

In the embodiment of FIG. 7 a transducer-side coupling element 58 has adovetailed portion 59, and the complementary receiving groove 52 isprovided in a micromanipulator-side coupling element 60 of thetransducer carriage 20. Apart from this reversal of the dovetailedportion and the complementary receiving groove, the embodiment of FIG. 7corresponds to that of FIG. 6.

In the embodiment of FIG. 8 the releasable coupling betweenmicromanipulator 18 and transducer 12 of FIG. 1 comprises amicromanipulator-side coupling element 62 defining an annular receiver61 which may be expanded and which is adapted to be locked in a closedposition. The micromanipulator-side coupling element 62 includes ashorter leg 63 and a longer leg 64. The legs 63, 64 are provided withcomplementary hook-shaped ends 65 and 66, respectively. The hooks 65, 66may be mutually disengaged for expanding the receiver 61 and fordetaching the transducer 12 from the micromanipulator 18 (FIG. 8 a). Thehooks 65, 66 at first also are disposed in this position when thetransducer 12 is to be connected to the micromanipulator 18. After theneck 38 of the transducer-side coupling element 22 has been introducedinto the receiver 61, pressure is applied to the longer leg 64 such thatthe hooks 65, 66 are engaged with each other (FIG. 8 b). In thisembodiment the transducer-side coupling element 22 may be mechanicallyrigid or elastic. At least the longer leg 64 of themicromanipulator-side coupling element 62 has spring characteristics.

FIG. 9 shows a further embodiment of the releasable coupling betweenmicromanipulator 18 and transducer 12. In this embodiment themicromanipulator-side coupling element 68 of the carriage 20 comprises apair of expandable tongs which are obtained in that a longitudinal slot69 separates the portion of carriage 20 remote from the spindle 34 intotwo elastic arms 70, 71. In the closed state of the tongs, free ends 72,73 of the arms 70, 71 define an annular receiver 74 for thetransducer-side coupling element 22. The slot 69 extends from thereceiver 74 towards the guide rail 28 of the micromanipulator 18. Thearms 70, 71 are spring-biased into an expanded position (FIG. 9 a) inwhich their free ends 72, 73 are disposed so as to permit thetransducer-side coupling element 22 to be inserted into the receiver 74and to be released from the receiver 74, respectively (arrow 76 in FIG.9 a). A slideable sleeve 75 extends around the coupling element 68.Sleeve 75 can be slideable moved along coupling element 68 between aposition in which the arms 70, 71 are released for expansion (FIG. 9 a)and a position closer to the free ends 72, 73 (arrows 77 in FIG. 9 b).In the latter position sleeve 75 urges the arms 70, 71 towards eachother against the spring biasing force until the ends 72, 73 enclose theneck 38 of the transducer-side coupling element 22 to thereby securelyhold the transducer-side coupling element together with the transducer12 (not shown) connected thereto (FIG. 9 b). In this embodiment thetransducer-side coupling element 22 may be mechanically rigid orelastic.

In all of the embodiments described above the transducer 12 and thetransducer-side coupling element 22 or 54 or 58, respectively, may befixedly interconnected, for example mechanically locked or securelyadhesively connected to each other. An integral interconnection oftransducer and transducer-side coupling element is also possible. Afurther alternative consists in securely connecting the transducer-sidecoupling element to the transducer, e.g. by a snap-in connection, notbefore implantation of the transducer. Then, if an exchange becomesnecessary, this transducer-side coupling element is supplied as aseparate exchangeable part together with a new transducer in a sterilepacking.

FIG. 10 shows a fully implantable hearing system having as actoricstimulation means an electromechanical output transducer 12 which isreleasably coupled to the micromanipulator 18 (which is not shown inFIG. 10 but particularly in FIG. 3) via a transducer-side couplingelement 22 or 54 or 58, respectively. The transducer 12 generally may beany electromagnetic, electrodynamic, piezoelectric, magnetostrictive, ordielectric (capacitive) transducer. A preferred embodiment of apiezoelectric transducer is known from commonly owned U.S. Pat. No.5,277,694 which is hereby incorporated by reference. Such a transduceris provided with a biocompatible cylindrical housing 78 (FIG. 3) ofelectrically conductive material, such as titanium. The housing 78 isfilled with an inert gas. An electrically conductive membrane that canoscillate, is disposed within the housing 78. The membrane preferably iscircular, and it is fixedly connected to housing 78 at the outer edgethereof A thin disk of piezoelectric material, e.g.lead-zirconate-titanate (PTZ), is provided at one side of the membrane.The side of the piezoelectric disk facing the membrane is inelectrically conductive connection with the membrane. Application of anelectrical voltage to the piezoelectric disk via a transducer line 79results in a deformation of the hetero-compound consisting of themembrane and the piezoelectric disk, and thus in a deflection of themembrane and of the coupling rod 14 attached thereto. Such a transducer12 typically has a relatively high mechanical output impedance,particularly a mechanical output impedance which is higher than themechanical load impedance of the biological structure of the middle earand/or the inner ear coupled to the transducer in the implanted state.The transducer 12, amongst others, may be modified in the mannerexplained in commonly owned U.S. Pat. No. 6,123,660, which is herebyincorporated by reference, such that a permanent magnet is attached atthe side of the piezoelectric ceramic disk remote from the membrane,which permanent magnet cooperates with an electromagnetic coil in themanner of an electromagnetic transducer. Such a combinedpiezoelectric-electromagnetic transducer is of advantage particularlywith respect to a broad frequency band and to attain relatively highoscillation amplitudes at relatively small amounts of supplied energy.The transducer 12 further may be an electromagnetic transducer of thetype described in commonly owned U.S. Pat. No. 6,162,169 which is herebyincorporated by reference.

To couple the electromechanical transducer 12 to the middle ear or theinner ear (for example to the incus at coupling site 80), especiallycoupling arrangements as described in commonly owned U.S. Pat. No.5,941,814, which is hereby incorporated by reference, are suited inwhich a coupling element, in addition to a coupling part for thepertinent coupling site, has a crimp sleeve which is first slippedloosely onto a rod-shaped part of a coupling rod connected to thetransducer in the above described manner. This rod-shaped part of thecoupling rod is provided with a rough surface. During implantation, thecrimp sleeve can simply be pushed and turned relative to the couplingrod to exactly align the coupling part of the coupling element with theintended coupling site. Then, the crimp sleeve is fixed by beingplastically cold-deformed by means of a crimping tool. Alternatively,the coupling element can be fixed with reference to the coupling rod bymeans of a belt loop which can be tightened.

Other coupling arrangements which can be preferably used here aredescribed, in particular, in commonly owned, co-pending U.S. patentapplications Ser. Nos. 09/576,009, 09/626,745, 09/613,560, 09/680,489and 09/680,488, all of which hereby are incorporated by reference. Thus,according to commonly owned, co-pending U.S. patent application Ser. No.09/576,009, a coupling element can have a contact surface on itscoupling end which has a surface shape which is matched to or can bematched to the surface shape of the coupling site, and has a surfacecomposition and surface size such that, by placing the coupling endagainst the coupling site, dynamic tension-compression force coupling ofthe coupling element and ossicular chain occur due to surface adhesionSer. which is sufficient for secure mutual connection of the couplingelement and the ossicular chain. The coupling element can be providedwith an attenuation element which adjoins the coupling site, in theimplanted state, and which has entropy-elastic properties in order toachieve an optimum form of vibration of the footplate of the stapes orof the membrane which closes the round window or an artificial window inthe cochlea, in the vestibulum or in the labyrinth, and especially tominimize the risk of damage to the natural structures in the area of thecoupling site during and after implantation (see commonly owned,co-pending U.S. patent application Ser. No. 09/626,745).

According to commonly owned co-pending U.S. patent application Ser. No.09/613,560 the coupling element can be provided with an actuation devicefor selectively moving the coupling element between an open position, inwhich the coupling element can engage and disengage the coupling site,and a closed positioning, in which the coupling element in the implantedstate is connected by force-fit and/or form-fit to the coupling site.

Furthermore, for mechanically coupling the electromechanical transducerto a pre-selected coupling site on the ossicular chain, a couplingarrangement (see commonly owned, co-pending U.S. patent application Ser.No. 09/680,489) is suitable which has a coupling rod which can be causedby the transducer to mechanically vibrate, and a coupling element whichcan be connected to the pre-selected coupling site. The coupling rod andthe coupling element are interconnected by at least one coupling, and atleast one section of the coupling element which, in the implanted state,adjoins the coupling site is designed for low-loss delivery ofvibrations to the coupling site, the first half of the coupling havingan outside contour with at least roughly the shape of a spherical domewhich can be accommodated in the inside contour of a second couplinghalf that is at least partially complementary to the outside contour.The coupling has the capacity to swivel and/or turn reversibly againstforces of friction, but is essentially rigid for the dynamic forceswhich occur in the implanted state. According to a modified embodimentof such a coupling arrangement (see commonly owned, co-pending U.S.patent application Ser. No. 09/680,488) the first half of the couplinghas an outside contour with an at least cylindrical, preferablycircularly cylindrical, shape which can be accommodated in the insidecontour of a second coupling half that is at least partiallycomplementary to the outside contour. A section of the coupling element,which adjoins the coupling site in the implanted state, is designed forlow-loss delivery of vibrations to the coupling site in the implantedstate, transmission of dynamic forces between the two halves of thecoupling taking place essentially in the direction of the lengthwiseaxis of the first coupling half The coupling can be reversibly coupledand de-coupled, and can be reversibly moved linearly and/or rotationallywith reference to the lengthwise axis of the first coupling half, but isrigid for the dynamic forces which occur in the implanted state.

The fully implantable hearing system shown in FIG. 10 further comprisesan implantable microphone (sound sensor) 82, a wireless remote control83 to control the implant functions by the implant wearer, and acharging system comprising a charger 84 and a charging coil 85 forwireless transcutaneous recharging of a secondary battery located in theimplant for power supply of the hearing system.

The microphone 82 can advantageously be built in the manner known fromcommonly owned U.S. Pat. No. 5,814,095 which hereby is incorporated byreference. Particularly, microphone 82 can be provided with a microphonecapsule which is accommodated hermetically sealed on all sides within ahousing, and with an electrical feed-through connector for routing atleast one electrical connection from within the housing to the outsidethereof The housing has at least two legs which are arranged at an anglerelative to one another, a first one of the legs containing themicrophone capsule and being provided with a sound inlet membrane, and asecond one of the legs containing the electrical feed-through connectorand being set back relative to the plane of the sound inlet membrane.The geometry of the microphone housing is chosen such that when themicrophone is implanted in the mastoid cavity the leg which contains thesound inlet membrane projects from the mastoid into an artificial holein the posterior bony wall of the auditory canal and the sound inletmembrane touches the skin of the wall of the auditory canal. To fix theimplanted microphone 82, there can preferably be a fixation element ofthe type known from commonly owned U.S. Pat. No. 5,999,632 which herebyis incorporated by reference. This fixation element has a sleeve, acylindrical housing part of which surrounds the leg which contains thesound inlet membrane, wherein the sleeve is provided with projecting,elastic flange parts which can be placed against the side of the wall ofthe auditory canal facing the skin of the auditory canal. The fixationelement preferably comprises a holding device which, beforeimplantation, maintains the flange parts mentioned above, against theelastic restoration force of the flange parts, in a bent position whichallows insertion through the hole of the wall of the auditory canal.

The charging coil 85 connected to the output of the charging device 84preferably forms part of the transmitting serial resonant circuit in themanner known from commonly owned U.S. Pat. No. 5,279,292 which hereby isincorporated by reference. The transmitting serial resonant circuit canbe inductively coupled to a receiving serial resonant circuit which isnot shown. The receiving serial resonant circuit can be part of theimplantable electronic module 86, and according to U.S. Pat. No.5,279,292, can form a constant current source for the battery. Thereceiving serial resonant circuit is connected in a battery chargingcircuit which, depending on the respective phase of the charging currentflowing in the charging circuit, is closed via one branch or the otherof a full wave rectifier bridge.

The electronic module 86 is connected in the arrangement as shown inFIG. 10 via a microphone line 87 to the microphone 82 and via thetransducer line 79 to the electromechanical transducer 12

FIG. 11 schematically shows the structure of a partially implantablehearing system. This partially implantable system includes a microphone89, an electronic module 90 for electronic signal processing, the powersupply (battery) 91 and a modulator/transmitter unit 92 in an externalmodule 93 which is to be worn externally on the body, preferably on thehead over the implant. As in known partial implants, the implant ispassive in terms of energy. Its electronic module 94 (without battery)receives its operating energy and control signals for the transducer 12via the modulator/transmitter unit 92 in the external module 93.

Both the fully implantable hearing system and the partially implantablehearing system may be designed as a monaural system (as illustrated inFIGS. 10 and 11) or as a binaural system. A binaural system forrehabilitation of a hearing disorder of both ears comprises a pair ofsystem units, each of which units is associated to one of the two ears.Both system units may be essentially identical to one another. But onesystem unit can also be designed as a master unit and the other systemunit as the slave unit which is controlled by the master unit. Thesignal processing modules of the two system units can communicate withone another in any way, especially via a wired implantable lineconnection or via a wireless connection, preferably a bidirectional highfrequency path, a bodyborne sound-coupled ultrasonic path or a datatransmission path which uses the electrical conductivity of the tissueof the implant wearer, such that in both system units optimized binauralsignal processing is achieved.

Particularly, the following possibilities of combinations are possible:

-   -   Both electronic modules may each contain a digital signal        processor, and the operating software of the two processors can        be transcutaneously changed, if required. Then the connection of        the two modules provides essentially for data exchange for        optimized binaural signal processing, for example, of the sensor        signals.    -   Only one module contains the digital signal processor. The        module connection then provides, in addition to transmission of        sensor data for binaural sound analysis and balancing, for        transfer of the output signal to the contralateral transducer,        wherein the latter module can house the electronic transducer        driver. In this case, the operating software of the entire        binaural system is filed in only one module, and the software        also is changed transcutaneously only in this module from the        outside via a telemetry unit which is present on only one side.        In this case, the power supply of the entire binaural system can        be housed in only one electronic module with power being        supplied by wire or wirelessly to the contralateral module.

While various embodiments in accordance with the present invention havebeen shown and described, it is understood that the invention is notlimited thereto. These embodiments may be changed, modified and furtherapplied by those skilled in the art. Therefore, this invention is notlimited to the details shown and described previously but also includesall such changes and modifications which are encompassed by the appendedclaims.

1. A method of implanting an at least partially implantable hearingsystem comprising: fixedly attaching a micromanipulator to the cranialvault of a recipient, said micromanipulator having a manipulator-sidecoupling attached thereto; positioning said micromanipulator in adesired position; fixedly connecting a transducer-side coupling elementto an electromechanical transducer in the course of an implantation ofsaid transducer; releasably coupling said micromanipulator to saidtransducer, comprising: snapping said transducer-side coupling elementinto said micromanipulator-side coupling element to mechanically locksaid transducer-side coupling element therein.
 2. The method of claim 1,further comprising: decoupling said transducer-side coupling elementfrom said micromanipulator-side coupling element, and removing saidtransducer from said recipient.
 3. The method of claim 2, furthercomprising: coupling a replacement transducer, having a transducer-sidecoupling element, to said micromanipulator.
 4. An at least partiallyimplantable hearing system comprising: at least one electromechanicaloutput transducer; a micromanipulator configured to be fixedly attachedto a recipient's cranial vault and, once so attached, to rotationallyand axially position, and fixedly retain, said at least one transducer;and a coupling unit, disposed between said transducer and saidmicromanipulator, configured to permit decoupling of said transducerfrom said micromanipulator while maintaining the position of saidmicromanipulator, comprising: a transducer-side coupling element,connected to said transducer, having a first configuration and an atleast partially deformed second configuration, a micromanipulator-sidecoupling element connected to said micromanipulator configured toreceive said transducer-side element, and wherein said transducer-sidecoupling element adopts said second configuration during insertion intosaid micromanipulator-side element, and regains said first configurationfollowing insertion, to thereby mechanically lock said transducer-sidecoupling element into said micromanipulator-side coupling element. 5.The device of claim 4, wherein said transducer-side coupling element isconfigured to be axially pressed into said micromanipulator-sidecoupling element.
 6. The device of claim 4, wherein said transducer-sidecoupling element is made of a resiliently flexible material.
 7. Thedevice of claim 4, wherein said micromanipulator-side coupling elementis a rigid annular receiver member.
 8. The device of claim 4, whereinsaid transducer-side coupling element is configured to decouple frommicromanipulator-side coupling element when said head is compressed atleast slightly.
 9. The device of claim 4, wherein said transducer-sidecoupling element comprises: a truncated head having an at leastpartially circular base; a cylindrical neck, connected to and alignedwith said base along an axis through the center of said base, extendinglongitudinally away from said base, and having a circumference that issmaller than that of said base, and a collar extending radially fromsaid neck at an end of said neck remote from said base.
 10. The deviceof claim 9, wherein said micromanipulator-side coupling elementcomprises: a circular cylindrical receiver having an inner diameter isapproximately the same as the outer of said neck, and an outer diameterthat is smaller than a diameter of said base.
 11. The device of claim 4,wherein said transducer-side coupling element is at least partially madeof elastic material.
 12. The system of claim 11, wherein said elasticmaterial is a polymeric material.